32bit to 64bit bridging to support varjo in openxr

[durandom]

I reached out to Varjo support and asked for a 32bit version of their runtime. Here's the reply:

very interesting project, we unfortunately have 3rd party dependencies also, so it's not just a recompile at the moment so it will be hard for us to prioritize and do it. I do think that only WMR does support the 32-bit runtime, wonder if it would be possible for you to do an interop to 64 bit instead fromt the 32 bit code. Did not try this myself but it might be something to consider. https://learn.microsoft.com/en-us/windows/win32/winprog64/process-interoperability and https://learn.microsoft.com/en-us/windows/win32/winprog64/interprocess-communication have some starting point at least. Please note that I did not try this, so it might not be suitable, just thought I share thoughts.

This is beyond my knowledge, but I think they suggest to make the openxr calls to the 64bit runtime dll via some interop middleware. Maybe this would require a 32bit openxr wrapper dll?! Just wanted to share here, maybe some folks with more knowledge can judge the feasability of this.

Maybe we can even get @mbucchia to weigh in. Sounds like a challenging enough problem :)